In the related art, among image forming apparatuses, there are apparatuses each performing double-sided printing by reversing a sheet after printing an image on one face of the sheet using an image forming unit and printing an image on the other face of the sheet by conveying the sheet to the image forming unit again (for example, see JP-A-2007-039203). An image forming apparatus disclosed in JP-A-2007-39203, for example, after printing an image on one face of a first sheet, supplies a second sheet from a supply device to a conveyance path and performs consecutive double-sided printing alternately for each of the two sheets. In this case, the image forming apparatus should appropriately control a sheet space between two sheets in order to suppress a collision between the first sheet and the second sheet. More specifically, the image forming apparatus should adjust a sheet space by controlling the conveyance speed of sheets at each point in the conveyance path and the like.
The image forming apparatus described above conveys a sheet having an image printed on one face to the image forming unit again through a circulation path. The circulation path branches from the middle of a sheet discharging path which is configured to connect a discharge port discharging the sheet and the image forming unit to each other, and the circulation path is connected to the upstream side of the image forming unit. In addition, a reversal path reversing a sheet branches from the middle of this circulation path. The image forming apparatus conveys a sheet having an image printed on one face from the circulation path to the reversal path, reverses the sheet, and conveys the sheet again up to the image forming unit through the circulation path.
In the conveyance path described above, the sheet discharging path and the reversal path are arranged as independent paths different from each other. In a case where the sheet discharging path and the reversal path are separately arranged, there may be a concern that the whole length of the conveyance path becomes long. For this reason, a space used for arranging the conveyance path should be large enough inside the apparatus. In addition, there may be a concern that, in accordance with an increase in the conveyance path, the numbers and the like of rollers and drive sources used for conveying a sheet may increase. Consequently, there may be a concern that the size of the image forming apparatus may become large.